If your tow rig doesn't have enough torque to easily pull boat up the ramp, then it doesn't have enough torque to be pulling the boat, period. And in 4WD Low in any truck I know of, any steering movement will potentially damage the lockers on dry pavement so every manual I've ever read says not to engage 4WD Low in dry surfaces (only snow/mud/dirt). So if you pull up and then make a turn, well you may have just broken your transmission or at least when you hear the grinding noise you'll remember to shut it off.

You are right, but exaggerating a little.
Pulling a boat up a ramp, even with some turning, is not going to damage your transfer case unless there is already a problem.

However, I still modified both my Land Cruisers are modified for AWD or 2wd low range.

Well for me, that's about 5 feet of pulling, and to get into 4wd low you usually have to put in neutral and wait for it to shift, I just don't see the reason at all, but more power to you if it works for you and you can remember all the steps every time.

Well for me, that's about 5 feet of pulling, and to get into 4wd low you usually have to put in neutral and wait for it to shift, I just don't see the reason at all, but more power to you if it works for you and you can remember all the steps every time.